Safety and activity of trastuzumab-containing therapies for the treatment of metastatic breast cancer: our long-term clinical experience (GOIM study)

Background: Trastuzumab is widely used as the treatment of choice for HER2-positive metastatic breast cancer (MBC). Patients and methods: Seventy patients, median age 57 years and range 31-81 years, were included in our retrospective analysis with the aim to evaluate safety and activity of trastuzurnab-containing therapies. Results: We observed for first-line treatment response rate (RR) 41 %, stable disease (SD) 47% and time to progression (TTP) 8 months (range 1-44). Corresponding numbers for second line were RR 23%, SD 62% and (TTP) 9 months (range 3-23) and beyond second line RR 22%, SD 78% and TTP) 9 months (range 4-19). Overall survival was 19.2 months (3-62 months), The median cumulative dose of trastuzumab administrated was 5286 mg (464-17 940 mg). Trastuzumab was well tolerated. Median left ventricular ejection function (LVEF) at baseline was 62% and at the end of treatment was 59%. The more relevant adverse events consisted of an asymptomatic decrease in LVEF to 40% (baseline 60%) and a grade 3 symptomatic increase in bilirubin. Conclusion: Trastuzumab-containing therapies in MBC show a good safety and toxicity profile and a remarkable activity even in heavily pretreated women. Patients should benefit from continued trastuzumab therapy, as shown by the maintenance of (TTP) even beyond second-line treatment.